Nutritional supplementation plays an important role in the production cost structure of various species of zootechnical interest. By including alternative resources such as by-products or animal viscera, we seek to reduce this economic index. In general, organs have important macro- and micronutrient contents, therefore, those that are not used for human consumption are subject to potential value addition.
The experimental evaluation period was 60 days, 20 individuals were used per replicate, weighing 0.25 g on average. Four treatments were evaluated: Control (commercial diet (CD) Guppy), 100% tilapia CD (T1), tilapia CD + bovine heart (T2) and tilapia CD + bovine kidney (T3). Control, T2 and T3 feeds were isoproteic diets, while T1 had a lower content of crude protein, but a greater contribution of crude fiber compared to the other treatments (Table 1).
The contribution of DHA by the viscera was partially reflected in the yields obtained in the T3 treatment. Growth indices were evaluated every 15 days, such as weight gain (GDP), conversion factor (FCR), specific growth rate (SGR), thermal growth coefficient (CTC), K factor (K), increase in standard length (iLE), fertility, age at first birth and mortality. No significant differences (p>0.05) were found between Control, T2, and T3 in GDP, iLE, SGR, CTC, FCR, and K, but T1 had lower values compared to the other treatments for these variables. Regarding the reproductive parameters, there were no significant differences (p>0.05) between treatments, but a trend was noted (p= 0.091) with lower fecundity for the T1 treatment concerning the other diets (Table 2).
Due to the positive and comparable productive results with the use of a very high-value commercial guppy feed, it is considered that the use of bovine viscera, in combination with low-cost commercial feed for omnivorous production species, is a technically and economically viable alternative.